<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>V-show V-if</title>
    <script src="../vue.js"></script>
</head>
<body>
<div id="app">
    <div class="error" v-if="!message">error</div>
    <textarea name="" id="" cols="30" rows="10" v-model="message"></textarea>
    <br>
    <button v-if="message">提交</button>
    <pre>{{$data|json}}</pre>
</div>
<script type="text/javascript">
    new Vue({
        el:"#app",
        data:{
            message:'',
        }
    })
</script>
</body>
</html>